Lewis thought concessive knowledge attributions (e.g., ‘I know that Harry is a zebra, but it might be that he’s just a cleverly disguised mule’) caused serious trouble for fallibilists. As he saw it, CKAs are overt statements of the fallibilist view and they are contradictory. Dougherty and Rysiew have argued that CKAs are pragmatically defective rather than semantically defective. Stanley thinks that their pragmatic response to Lewis fails, but the fallibilist cause is not lost because Lewis was wrong about the commitments of fallibilism. There are problems with Dougherty and Rysiew’s response to Stanley and there are problems with Stanley’s response to Lewis. I’ll offer a defense of fallibilism of my own and show that fallibilists needn’t worry about CKAs.